The present invention relates to radio frequency identification (RFID) systems for asset tracking, and in one embodiment to such systems for use in tracking pallets.
Pallets, containers, and other similar structures are used worldwide to aid in the transport of products of various kinds, and are preferred because they can be easily moved with the aid of a forklift truck, which may also be referred to as a forklift. The pallet can be loaded with products (which may be in containers or cartons, for example) at the end of a production process, moved to a storage or transport location, shipped, moved to another storage or transport location, and then moved to a location at which the products would be used or sold. Because the pallets can be lifted, moved, and stored easily, they make the transportation of products simple and fast.
Conventional pallets are square or rectangular and include reinforced areas beneath which the forks of a forklift can enter to lift the pallet. Some conventional pallets can receive the forks of a forklift from only two opposite sides of the pallet, and are referred to as xe2x80x9ctwo-wayxe2x80x9d pallets. Other pallets can receive the forks of a forklift from any of its four sides, and arc referred to as xe2x80x9cfour-wayxe2x80x9d pallets. An exemplary four-way pallet 10 is shown in FIG. 1 Typically pallets 10 are constructed of a wood such as fir or pine or man-made materials, and the individual pieces of the pallet are nailed, stapled, or otherwise fastened together. In other instances, a monolithic pallet can be provided, made for example from plastic. Assembled pallets can include horizontal wooden boards called deck boards 20. On the top of the pallet 10, the deck boards 20 are normally supported in the middle and along each edge by stringer boards 30. The stringer boards 30 may in turn be supported by blocks 40 provided at least at the four corners or vertices 50 of the pallet 10 and, perhaps, elsewhere along the outer edges 60 of the pallet or at its interior, or both. Other deck boards 20 (bottom deck boards) may be fastened to the underside of the blocks 40 to hold them in place, which can add rigidity and depending on the arrangement of those boards, can provide a top surface for the pallet if it is flipped over.
Assembled pallets normally include at least one board 20 at or near a side 60 of the pallet 10. Such a board is referred to as an xe2x80x9cend boardxe2x80x9d 80. The deck boards may be made from wood, plastic, or one or more other known materials. There are normally two end boards 80 per pallet 10, but four could be provided on, for example, a four-way pallet. Because of their position, end boards 80 are frequently damaged by the leading ends of the forks of a forklift, and for that and other reasons, molded plastic end boards are sometimes preferred. Plastic boards 20 may also be more uniformly sized and may provide greater resistance to the negative effects of moisture, such as mold or rotting.
RFID tags are now well-known and typically include an integrated circuit (IC) that is operatively coupled to an antenna (the tag antenna). The tag may also have a battery, or it may have no battery and may instead obtain energy from an external reader. RFID tags without batteries may be preferred for applications in which lower cost is a dominant factor, and RFID tags with batteries may be preferred for applications in which a longer read range is preferred. Either or both may be used in conjunction with the present invention. The RFID tags of the present invention preferably resonate in the UHF or microwave frequency band, either of which enables an RFID reader to interrogate the tags from a sufficiently long read range to be useful.
The IC associated with an RFID tag typically includes a certain amount of memory in which a tag identifier is stored, and perhaps other information related to the tag, and/or the item or items with which the tag is to be associated. When an RFID reader (also known as an interrogator, either of which may read or write information to an RFID tag) transmits energy via its reader antenna to interrogate the RFID tag, the tag responds with information from which the reader can obtain the RFID tag identifier or other information. The data, identifier, or information obtained by the RFID reader may then be compared to entries in a database of identifiers or to information associated with that RFID tag. In that manner, information regarding an RFID-tagged item may be obtained, updated, and provided to a user, and/or written to an RFID tag, perhaps even in real-time.
Various patents and publications have described the use of RFID tags with pallets. For example, publication document Netherlands 9401836 describes a process and system for the identification of pallets, in which an RFID tag (transponder) is installed in the center of the pallet. Antennae elements are provided in the forks of a pallet moving apparatus, which is supposed to enable a device to obtain information from the RFID tag. U.S. Pat. Nos. 5,662,048 and 5,971,592 also relate to a pallet having a data storage device from which a data collection device can obtain information. These and other sources do not, however, aid in the resolution of a number of practical difficulties that are resolved by the methods, systems, and devices of the present invention.
One aspect of the present invention provides an asset tracking system. One embodiment of the asset tracking system comprises: a) at least one RFID reader antenna positioned on a fixed portion of a forklift; b) at least one RFID reader antenna positioned on a portion of the forklift that is vertically movable with respect to the fixed portion; and c) a pallet including at least two RFID tags, in which one RFID tag is positioned in one quadrant of the pallet and another RFID tag is positioned in an opposite quadrant of the pallet, to enable at least one of the RFID tags to be interrogated by an RFID reader antenna adjacent any one of the four sides of the pallet.
Another aspect of the present invention provides a pallet. One embodiment of the pallet comprises: (a) a first REID tag provided in a first quadrant of the pallet; and (b) a second RFID tag provided in an opposed second quadrant of the pallet, such that an RFID reader antenna that approaches the pallet from one of the four sides of the pallet can interrogate at least one of the RFID tags.
Another aspect of the present invention provides a forklift RFID system. One embodiment of the forklift RFID system comprises: a) at least one RFID antenna positioned on a fixed portion of the forklift; and b) at least one RFID antenna positioned on a portion of the forklift that is vertically movable with respect to the fixed portion.
Another aspect of the present invention provides a forklift RFID system. One embodiment of the forklift RFID system comprises: (a) a forklift having a mast and a load backrest; and (b) at least one RFID antenna positioned within a column on each side of the forklift, the columns each being bounded by (i) the outer edge of the forklift mast; (ii) the outer edge of the forklift, (iii) the hack edge of the forklift mast, and (iv) the front edge of the load backrest.
Another aspect of the present invention provides a board for a pallet. One embodiment of the board for a pallet comprises a board for a pallet, wherein the board includes an edge and an RFID tag positioned at approximately a 45-degree angle with respect to that edge.
Another aspect of the present invention provides a pallet including a corner block. One embodiment of the pallet including a corner block comprises a pallet including a corner block, wherein the corner block includes a chamfered inside corner with an RFID tag affixed thereto.